John Osmon wrote:
Is anyone out there setting up routing boundaries differently for
IPv4 and IPv6? I'm setting up a network where it seems to make
sense to route IPv4, while bridging IPv6 -- but I can be talked
out of it rather easily.
Years ago, I worked on a academic network where we had a mix
of IPX, DECnet, Appletalk, and IP(v4). Not all of the routers
actually routed each protocol -- DECnet wasn't routable, and I recall
some routers that routed IPX, while bridging IP...
This all made sense at the time -- there were IPX networks that needed
to be split, while IP didn't need to be. DECnet was... DECnet -- and Appletalk was chatty, but useful.
I keep hearing the mantra in my head of: "I want my routers to route, and my switches to switch." I agree wholeheartedly if there is only one protocol -- but with the mix of IPv4 and IPv6, are there any folks
doing things differently? With a new protocol in the mix are the
lessons of the last 10 (or so) years not as clear-cut?
Hi John,
I remember old DECNET, DDCMP, IPX and NetBios days.
I used to have a couple of 19.2 kilobaud async lines, 2 arcnets and
an ethernet (thinwire technology but on RG13U cables, almost yellow wire
and UHF connectors - PL-259 like CB-radio).
DDCMP could route, IPX could and NetBios was riding on either IPX or
DDCMP so it did not matter.
Later the DDCMP async was replaced with a lots of switches and repeaters.
Whe used to have a backbone (yellow cable) connecting two VAXes and a
repeater that was feeding some 8 thinwires. Half of the thinwires were
feeding DECNET Terminalservers and PCs the other half were IPX with
a single one Netware server and lots of PCs.
In its best times the network was seeing some 1000 hosts. Everything
was running 10 MBit ethernet. there were 9 segments and no routers.
I have seen you could put some 30 NetBios PCs into a single segment
or more than 200 DECNET hosts if they were connected via switches and
thinwire transceivers.
Today without thinwire or yellow cable and with switches that can do
1 Gbit between switches and 100 Mbit to devices you should be able to
keep some 1000 hosts within a single switched network.
NAT-routers seem to have a limit of some 250 hosts within a single
255.255.255.0 network.
I dont know if those boxes really can do 250 or if their MAC address
tables break even earlier. I have seen those boxes missbehave when
a bad ethernet adapter randomly changed its MAC address.
There are quite some link local things in IPv6 so it makes a lot of
sense to keep them within a single network - beside that nasty /64
habit that suggests forget radvd and automatic addresses but have
an IPv4 address of the 192.168... variety and use 6to4 adressing
for your local network.
I was running my own network, 4 IPv4 networks and 3 IPv6 networks
without routers, only switches 
the 6to4 trick helped me survive
but now I dont know if the IPv6 boxes were really seeing each other
other simply using 6to4 routes
Kind regards
Peter and Karin